Tag Archives: Astronomy

Until the first high-altitude photographs were taken, the principal methods of cartography have been the same throughout the entire history.

If you are able to measure distances and angles, you have everything you need to map the world – this is the main focus of geodesy. Cartography then is just a trivial visual representation of geodetic data.

If you watch how the sun moves across the sky throughout the year, you will be able to see that the length of the sun’s path across the sky and the exact place where it rises and sets shifts as the months go by.

On the northern hemisphere, sun rises and sets at its northernmost point on the summer solstice (midsummer), and at its southernmost on the winter solstice. The equal point between these two extremes occurs at equinoxes, and if you connect the two opposite points on the horizon where the sun sets during the equinoxes, you can accurately determine the east-west axis.

The same thing applies to the celestial sphere. After observing it for a while it is very easy to come to a logical conclusion that it forms a sort of “sphere” that revolves around the earth, with its rotational axis fixed at Polaris, and the sun and the planets very slowly moving on trajectories close to the equator.

One of the main problems of very early cartography was that using the Sun or the Moon to measure the fixed four cardinal directions (north south, west east) was unreliable, as their positions in the sky significantly changed throughout the year and varied as the latitude changed.

The margin of error could be massive if one did not know the precise time of the year and did not have a precise enough way to measure angles, he could stray up to 25 km to the side from the intended target 100 km away.

However, the point at the horizon that is intersected by the celestial equator (stars that move the fastest during the night) is the same at any latitude, and if we know some of the constellations and stars that are very close to the equator, we can measure east and west with utmost accuracy. The most important of such stars is Mintaka, the uppermost star of the Orion’s belt. If one flew around the earth at the equator, basing his direction only by the position of Mintaka, he would never stray more than 31 km away from the equator. To determine where the north is, just find the point of horizon closest to the Polaris.

To measure more precise angles, you can either use lines that have been drawn in equal distances on a circular hoop or a semi-circular curved stick, or even a more precise instrument, such as this octant:

Of course, you also have to measure the distances between different landmarks and points on the coastline to make a maps. On the coasts of seas, lakes and rivers, you could simply aim to one direction and count your steps, trying not to deviate as much from the straight line, writing down the angular directions of every 100, 500, 1000 or more steps. Drawing an accurate coastline on mid-size maps of a tropical region and small maps of temperate regions is then trivial – draw a grid of small squares, mark your starting point, draw a continuous segmented line throughout the grid, with one segment being the fixed amount of steps you walked in one fixed direction.

Though most people did not really need maps when traveling on foot or horseback, as they usually followed already well-known paths and roads, cartography was extremely useful in the field of sea travel, as there were often no orientation points for thousands of miles and one could get lost very easily if he did not know how to determine his position with enough accuracy. Same process as when mapping land areas applies when measuring the length and relative angle of a distance traveled marine vessel, however, it is much more difficult to do it accurately, therefore distortions happen easily.

Mapping land regions from within was exceptionally accurate even in ancient times mainly because one could determine walking distances with a very high degree of accuracy. It was also often possible to create a very detailed and accurate map of more than a hundred square miles of land in a very short time just by climbing on a mountain of a decent height and looking around. This map of Europe was drawn in 200 AD by Ptolemy, and similar accuracies were not achieved in medieval Europe until about 14th century.

However, on the open sea, there are no discernible landforms one could peg his location to, and therefore determining the location of a ship on a latitude and longitude grid was always the only way to accurely estimate the distances between different continents and archipelagos. And this is difficult.So difficult, in fact, that it wasn’t until 1762 when the longitude relative to the Prime Meridian could finally be measured for the first time within a margin of error of 1 arc minute (±1 nautical mile), using a state-of-art chronometer H4, manufactured by John Harrison, who received an 18th century equivalent of a Nobel Prize because of it. However, these clocks remained quite expensive for a long time, and decreased below the sum of the annual wages of a skilled worker few years after Napoleon was exiled to St.Helena.

Until then, majority of sailors used the much less accurate method based on measuring the angles of the moon and various stars, and comparing them to values in a large astronomical almanac, determining the time at the Prime Meridian and longitudinal distance relative to it.

World maps only started to be very similar in their accuracy to those we hang on our walls in mid 19th century, however, it took well into the 20th century until the polar regions were finally thoroughly explored, with the last major blank spot being only filled in 1932, when the coastlines of the North Land Archipelago were finally charted.

‘‘I was sitting in the porch of the house at the trading station of Vanovara at 7 a.m. and looking towards the north . . . suddenly the sky appeared like it was split in two, high above the forest, the whole northern sky appeared to be completely covered with blazing fire. At that moment I felt a great wave of heat as if my shirt had caught fire… after a minute, there was a loud bang in the sky, and I could hear a mighty crash. Subsequently, I was fiercely thrown to the ground about 5-6 meters away from the house and for a minute or two I lost my consciousness.”

Farmer Sergei Semenov is only one of the few people who witnessed the Tunguska event on June 30, 1908, and survived. At the time of explosion, he was having a breakfast in trade station of Vanovara, located approximately 40 miles from the epicentre. What actually happened on that day? Early in the morning, on Tuesday 30.th of June 1908, there was a massive explosion in the area of Podkamennaya Tunguska, an unprecedented event uncomparable to anything in our modern history.

Aftermath of the 1908 Tunguska event

Closest seismograph, installed in Irkutsk, 600 miles from the epicentre, recorded strong vibrations lasting more than 60 minutes. Sound wave caused by the event encircled the planet multiple times. More than 800 kilometers away, in the city of Kansk, the noise was so loud that a train engineer stopped his train, thinking that one of the freight cars had exploded, and about 800 square miles of forests were flattened by the shockwave. However, any remnants of the object which caused this event are yet to be found.

According to the widely accepted theory, Tunguska event was caused by an asteroid air-burst on a grandiose scale(similar to 2013 Chelyabinsk event), which produced more than 30 megatons of energy.

Near the epicenter of Tunguska event(2008)

Both existing evidence and majority of scientists support this theory, however, soon after the explosion, incredible amount of other theories appeared, trying to explain the true nature of the Tunguska event. They range from scientifically based theories, supported by solid evidence, to various irrational hypotheses, often fabricated just to get attention. Let’s explore some of the other theories about the Tunguska Event, from scientific to plain ridiculous, and find out what really exploded in Siberia in year 1908.

4.Cometary Air-Burst

”Mathematical models indicate, that Tunguska event was actually caused by an explosion of small comet”, Moscow University professor Samuel Grigoryan claimed in year 1976.”Core of the comet is composed of frozen gasses, ice and cosmic dust. During its passage through the atmosphere, it would be rapidly heated, causing immediate evaporation and explosion. Released energy would correspond to the estimated 40 megatons”.

Visualisation of the Tunguska explosion

Although this theory, first suggested in 1930 by British meteorologist Francis Whipple, explains the strange luminous phenomena observed by the eyewitnesses of the Tunguska event, majority of scientists consider it being very improbable. Theyoften point out that a fragile cometary body ought to have already disintegrated in the uppermost layers of the atmosphere, whilst the object that caused the event apparently remained intact until it reached the lower atmospheric layers.

3.Collision with a miniature black hole, or piece of antimatter

According to many so-called ”experts”, Tunguska explosion was supposedly caused by annihilation, physical process that occurs when a subatomic particle collides with its respective antiparticle of the opposite charge, producing immense amounts of energy. According to this theory, first suggested in year 1941 by Lincoln LaPaz, the Tunguska event was likely caused by the annihilation of a chunk of antimatter colliding with Earth.

Although the antimatter theory explains the observed luminous phenomena, and why no remnants of asteroid or comet were found in the area, existence of such large antimatter chunks is often deemed being teoretically impossible. In addition, annihilation of the alleged chunk of antimatter would probably happen in the uppermost atmospheric levels.

Did a miniature black hole really cause the Tunguska event?

Another speculative hypothesis suggests, that the 1908 Siberian explosion was caused by a small black hole passing through Earth. This hypothesis was first formulated in year 1973 by American scientists Albert A. Jackson and Michael P. Ryan. However, as there was no exit event(second explosion, occuring as the black hole shot out in the North Atlantic), this hypothesis is considered wrong by majority of modern scientists. Other evidence, as dust trails and high-nickel concentrations around the impact area also dismiss this hypothesis.

2.Intervention of Agda, God of Thunder

Akulina, an Evenki woman, who was closer than 20 miles to epicentre at the time of explosion, later reported the event to the scientists: ”A mighty wind flattened our tent, while we had been sleeping. A brilliant ourburst of light blinded us, the wind was breaking trees like they were sticks. As a rising whirlwind lifted us off the ground, I lost conciousness”. After she woke up, she remembers seeking her husband, Ivan, being lifted up by blast, and slammed into one of the remaining upright trees, 130 feet from the remnants of the camp they had slept in. He died few hours later from fractures, shock and blood loss. ”Our reindeers also vanished, and we haven’t found them since”, Akulina also reported.

Group of Evenki people

If we can believe shamans of the Evenki tribe, who lived in the area for thousands of years, Tunguska event was caused by the Agda, the God of Thunder himself. Dissatisfied by the tribal disputes, Agda reputedly sent ”demons with shining eyes and fiery tails”, to punish the disobedient Evenki men.

Of course, we can’t take this explanation seriously. However, the fact remains that immediately after the event, the area was declared sacred and forbidden zone by Evenki tribesmen, who then reportedly expelled or killed dozens of Soviet scientific expeditions that ventured into the area of explosion decades after.

1.UFO Explosion

In year 1956, Russian sci-fi writer Alexander Kazancev published his short novel titled ”The Explosion”, with his own explanation about the true cause of the explosion. According to his version of the story, the Tunguska event was caused by the massive nuclear explosion of an extraterrestrial spaceship.

In year 1945, eleven years before the published the famous story, Kazantsev visited the ruins of the Hiroshima, city devastated by a nuclear explosion. Near the explosion’s epicenter, he noticed still-standing trees, with their leaves and branches ripped off by the sheer force of pressure wave. 6 years later, during his visit to Tunguska, he noticed similar patterns; no crater and standing trees without any branches or leaves. Because of that, he quickly comes to a conclusion; 1908 event had to be caused by a massive explosion, probably of nuclear origin.

Aftermath of the Tunguska explosion, (1929 explosion)

Another thing supporting the nuclear explosion theory are the burn marks on all trees around the epicenter. Forest fire caused by meteor explosion would burn the trees all around, however, marks only on one side indicate concentrated, short-term radiation heat, as during a nuclear explosion.

This hypothesis was further expanded by Valery Uvarov, director of the International UFO Network himself. Quoting his works: ”In northwestern Yakutia in Siberia, in the basin of the Upper Viliuy River, there is a hard-to-reach area, bearing the marks of tremendous cataclysm that took place some 800 years ago. Distributed across this area are mysterious metal objects located deep underground in the permafrost. The last time that this installation shot down a meteor was on 24/25 September last year.”